Insecticidal peptides are toxic to their targets when delivered internally, but sometimes they have little or no topical activity. Topical insecticidal activity refers to a toxin's ability to inhibit the growth, impair the movement or even kill an insect when the toxin is delivered to the insect or the insect's environment by spraying, or other means, as opposed to delivering the toxin directly to the insect's gut or internal organs by injection or inducing the insect to consume the toxin from its food, for example an insect feeding upon a transgenic plant.
The ability to successfully enhance or even change the properties of peptides with solvents has, until now, proven elusive. The wide variety, unique properties and special nature of peptides, combined with the huge variety of possible solvents one could choose from, has produced only a few described methods for the enhancement of a few selected peptides in the past 50 years or so. Various texts on the subject exist. See for example, Principles of Dairy Chemistry Jenness and Patton (1959) pp. 115-117, 127, 317, 326-328, 333.
Attempts have been made to enhance the activity of a few peptides through purification and extraction. For example, U.S. Pat. No. 5,840,838, Hensley, describes a procedure for enhancing the activity of amyloid β peptide, a 39-43 residue peptide, with a process that involves dissolving the peptide in an organic solvent, incubating it for 45 minutes to 3 hours above room temperature, equilibrating to room temperature and then removing the solvent.
U.S. Pat. No. 4,530,784, Rosenberg, relates to a method of extracting a biologically active factor that restores contact inhibition of growth to malignant cells in mammals by mixing specially prepared media with a volatile non-denaturing precipitating agent. The precipitate formed by this reaction is separated from the formulation and extracted with a biologically acceptable ionic buffering agent.
U.S. Pat. No. 4,337,194, Diaz, is a process of preparing somatostatin using a step-wise peptide coupling reaction in a solution of DMF. The product of the reaction is isolated by evaporation or by precipitation with a second solvent which renders the somatostatin insoluble, then the crude peptide obtained is purified.
There are few if any descriptions, however, for a method to convert a peptide which has low topical insecticidal activity into one having significantly greater topical insecticidal activity.
The procedure described here increases the topical insecticidal toxicity of insecticidal peptides. Peptides thus treated are referred to herein as “enhanced topical peptides.” The process described herein of making enhanced topical peptides is sometimes called making the peptides “special.” The process of making the peptides special makes the peptides more active than before they are treated with the process or treatment described herein. Once the peptides have been made special they can be applied topically to the insect, the insect's environment, to the places it inhabits, its habitat and to the food it touches, eats or consumes; in order to control the insect, rather than having to engineer the peptide into the genome of a suitable plant or other food. Both the new process, the formulations, and the new enhanced topical peptides produced by the process are described and claimed herein.